State of biodiversity in NZ

  • Otago skink. Image - Richard Gordon

    Otago skink. Image - Richard Gordon

Jamie Morton, NZ Herald, posed these questions to Manaaki Whenua – Landcare Research ecologist Dr Andrea Byrom, director of the New Zealand's Biological Heritage National Science Challenge, as part of his series on 50 Questions About the Environment: Our nature

How would you describe the general state of biodiversity in New Zealand? Is the decline of native species happening at a pace much faster than we realise?

Things are not looking good for the native plants and animals of New Zealand. Many of our threatened species such as tīeke (saddleback), kākā, Bartlett’s rātā, Otago skink and Giant Kōkopu appear to be in decline due to predation from introduced pests, spread of weeds, or loss of habitat.

The IUCN (International Union for the Conservation of Nature) ‘red list’ is a global inventory of the conservation status of species. New Zealand has more than 3000 native plants and animals listed as threatened or vulnerable, with about 800 of those listed as facing the risk of extinction. Some of our native biodiversity is ‘data deficient’ – meaning that we simply don’t know enough about these species to know how fast they are declining.

Many of our iconic bird species, such as the kākāpō, are intensively managed, and those that are less intensively managed, such as tūī, are only managing a comeback in places with intensive pest control. But those places are postage stamps compared to the scale of effort required.

The recent news that two species of kiwi have been removed from the endangered species category is welcome, but this is the exception rather than the rule. And just last week, kea, our cheeky mountain parrot, received the dubious honour of ‘endangered’ status.

And that’s just the things we can see: like many places, New Zealand has a wealth of cryptic fungi, bacteria and other microorganisms that probably play a vital role in ecosystem function. We simply don’t know how human activities such as land use intensification may affect the decline of these organisms.

What are the big drivers behind it and how have these trends changed over recent decades?

Invasive predators are one of the top threats to New Zealand’s native fauna. Whilst there is currently a lot of attention on the ‘top three’ being targeted by Predator Free New Zealand (rats, stoats and possums), we also have a number of other predators, such as ferrets, feral cats, and hedgehogs, that prey on the nests of ground-dwelling birds, and also eat native lizards and invertebrates (bugs).

And ecologists are also starting to turn their attention to house mice as a small but persistent predator of birds’ eggs, invertebrates, and lizards. Mice are everywhere, from urban gardens to mountaintops, so their national impact on our native fauna may be quite large.

Other major drivers include the spread of weeds such as Tradescantia (which can smother the regeneration of native plant seedlings), and intensification of land use. For example, in South Canterbury’s Mackenzie Basin, more than 80 species of rare plants and animals have been put at risk by irrigation and sowing of pasture grasses for agriculture.

Increasingly our changing climate is looking set to add another dimension to biodiversity decline – either directly, through warmer temperatures making habitat unsuitable (which may be occurring in some alpine ecosystems) or indirectly (for example, through increased frequency of tree seeding [masting] events increasing the impact of rodents and stoats in our forest ecosystems). A changing climate, bringing wind-borne spores of plant pathogens such as myrtle rust, also brings increasing pressure on at-risk plants such as the iconic Bartlett’s rātā.

Together these global environmental stressors (invasive pests, climate change, loss of habitat) mean that we should be paying much more attention to the decline of our biodiversity than we currently are – and we should have a comprehensive national strategy to reverse the decline.

It’s been 50 years since conservation pioneer Don Merton launched an effort that led to our first pest predator free island. Around 100 are now predator free. How would you describe the gains we’ve made over that time? Have they been meaningful?

Without out offshore islands as safe havens and refuges for our native birds in particular, many of them would now be extinct. New Zealand has made a huge effort to remove invasive predators from islands, and we are seen as a world leader in pest eradication and in island conservation and restoration.

However, our pest-free sanctuaries and offshore islands make up less than 2% of New Zealand’s land area. The big gains are yet to be made – on larger offshore islands such as Resolution and Secretary Islands in Fiordland, and on human-inhabited islands like Waiheke, Rakiura (Stewart Island) and Aotea (Great Barrier).

The Department of Conservation has made significant gains in removing stoats from Secretary and Resolution Islands, although they haven’t quite achieved eradication yet. And there are amazing community-led pest control initiatives on Waiheke, Rakiura and Aotea already, but support from the whole community will be required to take the extra step to eradication.

It’s also been a year and a half since the previous government announced plans to make the country predator free by 2050. Given what we know about the challenges of pest eradication, can this be done?

A lot of people ask me this question and I always say: it can’t be done right now, but in a couple of decades I hope it will be within sight. We have a lot of tools in the toolbox already, but we will need the support of people from all walks of life to achieve such an ambitious goal. We will also need novel technolgies – things we probably haven’t thought of yet – to get there.

There are many hopeful signs however. Almost every day I see an announcement for another community-led pest control initiative. There are hundreds of them around the country – the community support for Predator-Free is significant and growing. Also, some of the larger, regional-scale predator control initiatives like Cape to City in Hawkes Bay, Taranaki Mounga, and Predator-Free Dunedin are leading the way in bringing conservationists and primary industries, iwi, hapū, and communities together. A few more initiatives like these and we’ll have a chunk of the country covered.

It’s been stated that some game-changing science will be needed for the job. Do you believe we’ll need to embrace gene-editing technology to be able to achieve the goal? And what other solutions might help get us there?

The need for new technologies in pest management in New Zealand is not new: people have identified the need for novel tools to add to the toolbox for more than two decades.

The issue is scale. Most methods using traps and toxins cost somewhere between $10 per hectare (if pests are already at low density) and $20 per hectare (aerial control). To scale up existing methods to the entire country has been estimated to cost more than $9B. That means we need to innovate to get to the goal.

Genetic technologies are being investigated as one possibility: if they are cheaper per hectare, we could cover more land area. Gene editing (for example, inserting a gene for male infertility and using CRISPR to ‘self replicate’ through a population) is one possibility. It is still highly theoretical, and is currently being investigated overseas to determine whether it is possible to edit a gene for resistance to malaria in mosquitoes.

There are other options. For example, scientists are investigating the ‘Trojan Female Technique’ which selects for a natural variation in male infertility that is transmitted only through females. Species-selective toxicants, such as a rat-specific toxin, would be very useful on farmland where they did not affect dogs or livestock. There is also a technique called ‘gene silencing’, which is used to suppress the expression of an important trait or to disrupt metabolism. This is being investigated to detemine whether it could be used to reduce wasp populations.

The development and use of new genetic technologies will require a large amount of public consultation. On the other hand, their use may be more acceptable to people who hold concerns about the use of toxins in the environment. The idea of animals simply being unable to find a mate, eventually dying out naturally, is appealing to some.

We’ve read a lot about the importance and value of community conservation efforts, philanthropic support and public-private partnerships, such as Predator Free New Zealand, in conservation. Do you see any issues or problems with looking to groups or efforts outside government and councils to protect our biodiversity?

Conservation and protection of New Zealand’s plants and animals is everyone’s responsibility, wherever they live. It’s important for local and regional government to play a leadership role, but I don’t believe it is their responsibility alone. Others have been, and are, stepping up. In some cases that investment is significant. We need the involvement of philanthropists and the business community, working alongside iwi and hapu, resource managers, community restoration groups, private landowners, and others all playing their part. I believe that if governments have clear guidelines around which types of investment are appropriate, and if investors are respectful of the local communities they choose to work with, then it can be a win-win for everyone.

Following on from that question, do you feel more resources are needed from central government to tackle the issue? This includes more funding for front-line conservation, and more funding and resources for science and scientists.

We have certainly seen relatively minimal investment in conservation and biodiversity over the last decade or so from government. For example, the Threatened Species Strategy had no new funding attached to it when it was announced. I hope that may change now – the new government has indicated a strong desire to have the environment at the heart of its work.

I do believe it is time for more investment in the environment (via government departments), and I also believe that funding for environmental science has not always been given the priority it should. However, along with extra investment comes a responsibility: to spend any new funds wisely on top priorities, and to cooperate as much as possible across organisations in order to receive maximum value and impact from any new research investment. That is what the Science Challenges were established to do.

There’s also been much discussion about tourism and conservation. Do you feel tourism is paying its way to help our biodiversity?

I think we have seen some great examples where the tourism sector has partnered effectively with conservation – for example, Air New Zealand promoting the Department of Conservation’s Great Walks. However, the sector could probably do more to help protect the plants and animals that international tourists come here to see. The former Parliamentary Commissioner for the Environment recommended a tourism levy, and I believe New Zealand should explore that concept as a way of generating extra funds for conservation and biodiversity protection.

Do you think there’s a good amount of general awareness and appreciation from Kiwis of our biodiversity?

As New Zealanders we don’t always realise how lucky we are: we have some of the most unique biological taonga (treasures) on the planet. Yet many people are only vaguely aware of the decline of our plants and animals. I say to anyone who will listen: we need a biodiversity forecast on national TV every night, along with the weather forecast and the stock market results. This would be one means of raising awareness and public support for the concept of kaitiakitanga (guardianship) of biodiversity, because when local and regional governments can see that their constituents value biodiversity, they respond.

Into the future, what do you consider will be the big pressures on our biodiversity? What new or emerging ones might we have to overcome?

I can see two emerging problems. The first problem is people. Unless we can raise awareness of our biodiversity decline, and provide people with opportunities to do something in their local area, our species will continue to slide towards extinction. However, people are also an opportunity, because we hold the key to turning the situation around. The second problem is complexity. As I mentioned above, the biggest impact will be not from invasive predators or climate change or land use change alone. When all three come together, it will be a perfect storm, and very complex for scientists and traditional knowledge holders to untangle and help resource managers and kaitiaki respond. Protecting our biodiversity is everyone’s business, so building awareness amongst the community and turning it into action will be our biggest challenge.